Technical Field
The present disclosure relates to an electrosurgical system and method and, more particularly, to pulse sequencing to minimize current draw on a shared power supply.
Background of Related Art
Energy-based tissue treatment is well known in the art. Various types of energy (e.g., electrical, ohmic, resistive, ultrasonic, microwave, cryogenic, laser, etc.) are applied to tissue to achieve a desired result. Electrosurgery involves application of high radio frequency electrical current to a surgical site to cut, ablate, coagulate or seal tissue. In monopolar electrosurgery, a source or active electrode delivers radio frequency energy from the electrosurgical generator to the tissue and a return electrode carries the current back to the generator. In bipolar electrosurgery, one of the electrodes of the hand-held instrument functions as the active electrode and the other as the return electrode. The return electrode is placed in close proximity to the active electrode such that an electrical circuit is formed between the two electrodes (e.g., electrosurgical forceps). In this manner, the applied electrical current is limited to the body tissue positioned between the electrodes.
Typically, multiple isolated power supplies are connected to the active terminals of the electrosurgical generator to power analog circuits associated with components connected to the electrosurgical generator (e.g., bipolar instruments, monopolar instruments, footswitches, etc.). For example, analog circuits configured to detect connected components and/or switching thereof may be included within the generator or within the connected components. Often, these isolated power supplies share the same low voltage power source. This is problematic when multiple supplies draw power from the shared power source substantially simultaneously, thereby maximizing the peak current draw on the shared power source. For example, the combined primary currents generated by certain isolated power supplies activated substantially simultaneously may be large enough to cause a decrease in output of the shared power source due to its output impedance or internal resistance. This decrease in output may cause output noise on the analog circuits drawing power therefrom, if those analog circuits do not have adequate power supply rejection bandwidth at the switching frequency of the isolated power supply to which they are connected.